From 9b0bed19489dbbd59c52a77e9c0c080a880ca262 Mon Sep 17 00:00:00 2001
From: "John St. John" <jstjohn@users.noreply.github.com>
Date: Thu, 21 Sep 2017 16:28:23 -0700
Subject: Jstjohn/google stackdriver trace (#64)

Add app-level tracing to driver-core (https://www.pivotaltracker.com/story/show/151100422)
---
 .../trace/GoogleStackdriverTraceWithConsumer.scala | 75 ++++++++++++++++++++++
 1 file changed, 75 insertions(+)
 create mode 100644 src/main/scala/xyz/driver/core/trace/GoogleStackdriverTraceWithConsumer.scala

(limited to 'src/main/scala/xyz/driver/core/trace/GoogleStackdriverTraceWithConsumer.scala')

diff --git a/src/main/scala/xyz/driver/core/trace/GoogleStackdriverTraceWithConsumer.scala b/src/main/scala/xyz/driver/core/trace/GoogleStackdriverTraceWithConsumer.scala
new file mode 100644
index 0000000..7fed3c7
--- /dev/null
+++ b/src/main/scala/xyz/driver/core/trace/GoogleStackdriverTraceWithConsumer.scala
@@ -0,0 +1,75 @@
+package xyz.driver.core.trace
+
+import akka.http.scaladsl.model.HttpRequest
+import com.google.cloud.trace.core._
+import com.google.cloud.trace.sink.TraceSink
+import com.google.cloud.trace.v1.TraceSinkV1
+import com.google.cloud.trace.v1.consumer.{SizedBufferingTraceConsumer, TraceConsumer}
+import com.google.cloud.trace.v1.producer.TraceProducer
+import com.google.cloud.trace.v1.util.RoughTraceSizer
+import com.google.cloud.trace.{SpanContextHandler, SpanContextHandlerTracer, Tracer}
+
+import scala.compat.java8.OptionConverters._
+
+final class GoogleStackdriverTraceWithConsumer(projectId: String,
+                                               appName: String,
+                                               appEnvironment: String,
+                                               traceConsumer: TraceConsumer)
+    extends GoogleServiceTracer {
+
+  private val traceProducer: TraceProducer = new TraceProducer()
+  private val threadSafeBufferingTraceConsumer =
+    new SizedBufferingTraceConsumer(traceConsumer, new RoughTraceSizer(), 100)
+
+  private val traceSink: TraceSink = new TraceSinkV1(projectId, traceProducer, threadSafeBufferingTraceConsumer)
+
+  private val spanContextFactory: SpanContextFactory = new SpanContextFactory(
+    new ConstantTraceOptionsFactory(true, true))
+  private val timestampFactory: TimestampFactory = new JavaTimestampFactory()
+
+  override def startSpan(httpRequest: HttpRequest): TracerSpanPayload = {
+    val parentHeaderOption: Option[akka.http.javadsl.model.HttpHeader] =
+      httpRequest.getHeader(TracingHeaderKey).asScala
+    val (spanContext: SpanContext, spanKind: SpanKind) = parentHeaderOption.fold {
+      (spanContextFactory.initialContext(), SpanKind.RPC_CLIENT)
+    } { parentHeader =>
+      (spanContextFactory.fromHeader(parentHeader.value()), SpanKind.RPC_SERVER)
+    }
+
+    val contextHandler: SpanContextHandler = new SimpleSpanContextHandler(spanContext)
+    val httpMethod                         = httpRequest.method.value
+    val httpHost                           = httpRequest.uri.authority.host.address()
+    val httpRelative                       = httpRequest.uri.toRelative.toString()
+    val tracer: Tracer                     = new SpanContextHandlerTracer(traceSink, contextHandler, spanContextFactory, timestampFactory)
+    // Create a span using the given timestamps.
+    // https://cloud.google.com/trace/docs/reference/v1/rest/v1/projects.traces#TraceSpan
+    val spanOptions: StartSpanOptions = (new StartSpanOptions()).setSpanKind(spanKind)
+
+    val spanLabelBuilder = Labels
+      .builder()
+      .add("/http/method", httpMethod)
+      .add("/http/url", httpRelative)
+      .add("/http/host", httpHost)
+      .add("/component", appName)
+      .add("/environment", appEnvironment)
+
+    parentHeaderOption.foreach { parentHeader =>
+      spanLabelBuilder.add("/span/parent", parentHeader.value())
+    }
+
+    // The cloudTrace analysis reporting UI makes it easy to query by name prefix.
+    // this spanName gives us the ability to grab things that are specific to a particular UDE/env, as well as all
+    // endpoints in that service, as well as a particular endpoint in a particular environment/service.
+    val spanName: String = s"($appEnvironment->$appName)$httpRelative"
+
+    val context: TraceContext = tracer.startSpan(spanName, spanOptions)
+    tracer.annotateSpan(context, spanLabelBuilder.build())
+    GoogleStackdriverTraceSpan(tracer, context)
+  }
+
+  override def endSpan(span: TracerSpanPayload): Unit = {
+    span.tracer.endSpan(span.context)
+    threadSafeBufferingTraceConsumer.flush() // flush out the thread safe buffer
+  }
+
+}
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